1Chalupa W. Manipulation of rumen fementation[J].J. Anim. Sci.,1977(45):585-599.
2Wilson R C, Overton T R, Clark J H. Effect of yucca shidigera extract and soluble protein on performance of cows and concentration of urea nitrogen in plasma and milk[J]. J Dairy Sci.,1998(81):1022-1032.
3Hristov A N, McAllister T A, Van Herk F H, et al. Effect of Yucca schidigera on ruminal fermentation and nutrient digestion in heifers[J].J. Anim. Sci., 1999(77):2 554-2 263.
